1. Field of the Invention
The present invention relates to the production of semiconductor devices, and more particularly, to a method and an apparatus for vacuum treating and heating a semiconductor substrate. The present invention can be suitably applied to form a thin layer of a conductor, insulator or semiconductor on a semiconductor substrate.
2. Description of the Prior Art
Aluminum (Al) has been generally used as a material for electrodes and conductor lines of semiconductor devices. The aluminum is deposited on a semiconductor substrate, usually by a vacuum evaporation method to form a thin aluminum layer.
Recently, in addition to aluminum, aluminum alloys (e.g., Al-Si, Al-Si-Cu), refractory metals (e.g., tungsten, molybdenum) and silicides of the refractory metals have come into use for the electrodes and conductor lines. The formation of a thin layer of the metals and silicides has primarily been effected by a sputtering method, since the vacuum evaporation method is unsuitable for refractory metals and cannot easily control an alloy composition of the formed thin layer.
When the sputtering method is used to deposit one of the above materials on a semiconductor substrate to form a thin layer, the substrate is heated at an elevated temperature to prevent the electrodes and conductor lines from disconnecting at the shoulder portions of the uneven surface of the substrate, decrease the resistivity, prevent electromigration, provide a smooth surface, and increase the grain size.
In order to increase the substrate temperature in a conventional magnetron sputtering apparatus, a heater, e.g., at least one infrared lamp is placed in a vacuum treating chamber. In the case of a planetary type magnetron sputtering apparatus for batch treatment, the holder supporting the semiconductor substrates is rotated and heated up. Therefore, the size of the planetary type holder must be made much larger along with the diameter of the substrates. In practice, it is not always easy to make a heating system to increase the substrate temperature sufficiently. Even if such a heating system can be made, the heater will heat other portions of the apparatus requiring no heating, resulting in outgassing from these parts and poor operation of moving parts. In another type of magnetron sputtering apparatus, the sputtering treatment is carried out in an in-line system. In this case, the apparatus can be made smaller. However, it is difficult to satisfactorily heat the semiconductor substrates in a short time in the vacuum treating chamber. Accordingly, the substrates have to be preheated. Even in this type of apparatus, it is not easy to heat the substrates in the vacuum treating chamber. In practice, the substrates are only heated to an unsatisfactory degree.